About filters

Perhaps the most important part of Micro-Irrigation system design is the attention to treatment of the irrigation water before it enters the pipelines, tube, drip emitters or drip heads. The best possible irrigation system design using the best Micro-Irrigation products available will have little chance of success without careful filtration and treatment of any contaminants that are present in the proposed water source. A non-existing or poorly designed and installed filtration system can allow these contaminants to enter the distributing system and migrate to the final emitters. Since Micro-Irrigation (drip or spray) is designed with very small discharge openings, they can be partially or totally blocked by a number of types of contaminants found in irrigation water. In general there are two types of contaminants that must be removed from Micro-Irrigation water:

1. Inorganic (or "hard") materials: sand or any particulate that does not change its shape under system pressure. These contaminants can be removed by a screen-type filter system.
2. Organic (or "soft") Materials: algae, iron slime or any material, which can change shape and extrude trough a screen filter. These contaminants are best removed by a sand media or disk filter systems, which is also excellent for "hard" material filtration.

A laboratory analysis of any proposed irrigation water source is advisable to identify the filter system required.

Micro-Irrigation filter systems (screen, disc or sand) are rated by:

1. System flow-rate capacity, which is the volume of water in gallons per minute (GPM) to be filtered.
2. Mesh rating which indicates the dimension of the smallest particle allowed through the filter.

Both of these ratings are important in the selection of filtration equipment.

Note: Injection of chemicals into irrigation water has become common, particularly when Micro-Irrigation Systems are used. Some of these chemicals have the capacity to improve water quality but should never be presumed to be substitutes for the mechanical removal of particulates by filtration.

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